Helping Nonresponders Respond to Cardiac Resynchronization Therapy
Date: January 6, 2014
North Carolina resident Susan Brinkley received a biventricular implanted cardiac defibrillator for cardiomyopathy and atrial fibrillation in the fall of 2012. She had hoped that the therapy would restore her energy level so that she could once again lead an active life with her four children and 10 grandchildren. Instead, she says, “as the months went by, I continued to be exhausted, and I wasn’t feeling any better.”
“Cardiac resynchronization therapy (CRT) is one of the most important treatments for heart failure, but only six or seven out of every 10 patients respond,” says cardiac electrophysiologist John Rickard. “For the others, the prognosis for survival is very poor unless something is done—and there are things we can do to help many of these patients who are not responding to the therapy.”
Rickard is director of the Johns Hopkins Resynchronization Optimization Clinic, a new program designed to thoroughly evaluate the reasons why particular patients are not responding to CRT and provide recommendations to referring physicians on how to help patients benefit from the therapy.
Patients referred to the clinic receive a full assessment of their health and comorbidities, medications and diet, as well as an evaluation of how their pacemaker/defibrillator is functioning and specific problems with the device.
Because her condition was not improving, Brinkley’s daughter suggested that she come to Baltimore for an evaluation by Hugh Calkins. “After meeting with him, it was the greatest relief,” Brinkley says. “He had a specific plan. He checked the defibrillator, adjusted my medication and referred me to Dr. Rickard for a more detailed evaluation.”
“During the two-and-a-half-hour clinic visit,” says Rickard, “we perform a complete electrical analysis of the device, including EKGs with the device turned on and off to give us an idea of the morphology of the CRT-paced waveform. Patients also have an echocardiogram to see the function of the device in real time and lab tests to look for anemia or renal dysfunction.”
Often, the remedy is as straightforward as adjusting the existing device, getting a patient’s obstructive sleep apnea under control or modifying heart failure medications. At other times, a more complex intervention may be necessary by moving the left ventricular lead or considering the addition of a second left ventricular lead.
In Brinkley’s case, Rickard noticed that the left ventricular (LV) lead was not capturing because it wasn’t getting enough energy. “It was pacing the right ventricular (RV) lead all of the time and not the left, which can make the heart failure worse.”
To correct it, Rickard increased the voltage on the LV lead, capturing both sides so that it would function properly. He also adjusted the timing on the device, giving the LV lead a 20 millisecond head start before the firing of the RV lead.
“I’m so grateful to Dr. Calkins and Dr. Rickard,” Brinkley says. “They took the time to figure out the problem.”
Rickard recommends that all patients with CRT be evaluated within six to nine months after the device is put in. “If the patient is not feeling well, if the ejection fraction hasn’t improved and especially if it has gotten worse, then alarm bells should ring,” he says.
Rickard sees the goal for the specialized clinic as a way to not only improve patient survival but also to reduce hospitalization and readmission due to heart failure.